http://soa.utexas.edu/work/eaejp/Methods/Mental%20map%20from%206th%20grade-f.jpg
This is a map created by a 6th grader at Zavala Elementary School in Austin, TX. This is a great example of a mental map for several reasons. At first glance, you can tell that this map wasn't intended for serious use. It's probably made with crayons and markers. Aside from the cosmetics, glance at the homes on the map. There's one located in the middle of the street on Santa Maria and the others are just placed randomly on the grass. The student who drew this map isn't going for scientific accuracy. Instead they just drew what they knew and explained it the only way possible.
Below I posted a map from Google Maps. You can clearly see that there is much information left out of the students map, but the whole point of a mental map is that you only display what you feel is important. What do you think the student who made this mental map is trying to convey?
Google Maps link to Zavala Elem School